The immune system is changed during pregnancy, which can make expecting mothers more susceptible to these types of bacteria, according to Dr. Pamela Schultz, an Oakhurst obstetrician-gynecologist who is affiliated with Jersey Shore University Medical Center.

Bacteria, especially listeria, can be harmful to a growing fetus, leading in severe cases to miscarriages or early delivery, says Dr. Rebecca Cipriano, an ob-gyn with offices in Freehold and Colts Neck.

"Food that we say to avoid are foods that are left out for more than two hours, usually we're talking about cold cuts, deli meats, ready-to-eat meals," said Cipriano, a member of the CentraState medical staff. "You must be very careful with how you're handling fresh chicken or turkey."

Nothing raw or undercooked, and all fruits vegetables should be washed thoroughly. Anything with raw milk or eggs as an ingredient, like certain cheeses,or salad dressings, should be bypassed.

Tilefish, shark, swordfish, and king mackerel are to be avoided, while consumption of white albacore tuna should be limited to 6 ounces per week. Other seafood, such as shrimp, pollock, salmon, tilapia, catfish and cod, are fine in moderation, Schultz said, adding pregnant women should stick to familiar fare.

"Everything in moderation," she said. "Pregnancy is not the time to start trying new foods and new restaurants that you haven't been to."

Those guidelines, Cipriano said, apply to women who think they are pregnant, are trying to get pregnant or are breastfeeding, but don't get too worked up over an isolated incident.

"If you've just had a tuna fish sandwich it's not time to panic," she said.

Alcohol remains off limits, but caffeine is in a gray area. A cup of coffee a day probably isn't a big deal, Schultz said.

"Talk to your doctor, have a list of questions," she said. "Better to ask and be safe than to be sorry."

Russ Zimmer: 732-557-5748, razimmer@app.com

Options for safer eating

• Want a soft cheese like brie? Try cheddar or gouda instead.

• How about sushi? Stick to fully cooked fish or seafood.

• Can I get a deli meat sandwich? Grill you sandwiches, or the meat itself, until it is steaming hot.